From: Sean Christopherson <seanjc@google.com>
To: Marc Zyngier <maz@kernel.org>,
Huacai Chen <chenhuacai@kernel.org>,
Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
Paul Mackerras <paulus@ozlabs.org>,
Anup Patel <anup.patel@wdc.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Janosch Frank <frankja@linux.ibm.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Atish Patra <atish.patra@wdc.com>,
David Hildenbrand <david@redhat.com>,
Cornelia Huck <cohuck@redhat.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org,
kvm@vger.kernel.org, kvm-ppc@vger.kernel.org,
kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org,
linux-kernel@vger.kernel.org, Ben Gardon <bgardon@google.com>,
"Maciej S . Szmigiero" <maciej.szmigiero@oracle.com>
Subject: [PATCH v5.5 01/30] KVM: Ensure local memslot copies operate on up-to-date arch-specific data
Date: Thu, 4 Nov 2021 00:25:02 +0000 [thread overview]
Message-ID: <20211104002531.1176691-2-seanjc@google.com> (raw)
In-Reply-To: <20211104002531.1176691-1-seanjc@google.com>
When modifying memslots, snapshot the "old" memslot and copy it to the
"new" memslot's arch data after (re)acquiring slots_arch_lock. x86 can
change a memslot's arch data while memslot updates are in-progress so
long as it holds slots_arch_lock, thus snapshotting a memslot without
holding the lock can result in the consumption of stale data.
Fixes: b10a038e84d1 ("KVM: mmu: Add slots_arch_lock for memslot arch fields")
Cc: stable@vger.kernel.org
Cc: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
virt/kvm/kvm_main.c | 47 ++++++++++++++++++++++++++++++---------------
1 file changed, 31 insertions(+), 16 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 3f6d450355f0..99e69375c4c9 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1531,11 +1531,10 @@ static struct kvm_memslots *kvm_dup_memslots(struct kvm_memslots *old,
static int kvm_set_memslot(struct kvm *kvm,
const struct kvm_userspace_memory_region *mem,
- struct kvm_memory_slot *old,
struct kvm_memory_slot *new, int as_id,
enum kvm_mr_change change)
{
- struct kvm_memory_slot *slot;
+ struct kvm_memory_slot *slot, old;
struct kvm_memslots *slots;
int r;
@@ -1566,7 +1565,7 @@ static int kvm_set_memslot(struct kvm *kvm,
* Note, the INVALID flag needs to be in the appropriate entry
* in the freshly allocated memslots, not in @old or @new.
*/
- slot = id_to_memslot(slots, old->id);
+ slot = id_to_memslot(slots, new->id);
slot->flags |= KVM_MEMSLOT_INVALID;
/*
@@ -1597,6 +1596,26 @@ static int kvm_set_memslot(struct kvm *kvm,
kvm_copy_memslots(slots, __kvm_memslots(kvm, as_id));
}
+ /*
+ * Make a full copy of the old memslot, the pointer will become stale
+ * when the memslots are re-sorted by update_memslots(), and the old
+ * memslot needs to be referenced after calling update_memslots(), e.g.
+ * to free its resources and for arch specific behavior. This needs to
+ * happen *after* (re)acquiring slots_arch_lock.
+ */
+ slot = id_to_memslot(slots, new->id);
+ if (slot) {
+ old = *slot;
+ } else {
+ WARN_ON_ONCE(change != KVM_MR_CREATE);
+ memset(&old, 0, sizeof(old));
+ old.id = new->id;
+ old.as_id = as_id;
+ }
+
+ /* Copy the arch-specific data, again after (re)acquiring slots_arch_lock. */
+ memcpy(&new->arch, &old.arch, sizeof(old.arch));
+
r = kvm_arch_prepare_memory_region(kvm, new, mem, change);
if (r)
goto out_slots;
@@ -1604,14 +1623,18 @@ static int kvm_set_memslot(struct kvm *kvm,
update_memslots(slots, new, change);
slots = install_new_memslots(kvm, as_id, slots);
- kvm_arch_commit_memory_region(kvm, mem, old, new, change);
+ kvm_arch_commit_memory_region(kvm, mem, &old, new, change);
+
+ /* Free the old memslot's metadata. Note, this is the full copy!!! */
+ if (change == KVM_MR_DELETE)
+ kvm_free_memslot(kvm, &old);
kvfree(slots);
return 0;
out_slots:
if (change == KVM_MR_DELETE || change == KVM_MR_MOVE) {
- slot = id_to_memslot(slots, old->id);
+ slot = id_to_memslot(slots, new->id);
slot->flags &= ~KVM_MEMSLOT_INVALID;
slots = install_new_memslots(kvm, as_id, slots);
} else {
@@ -1626,7 +1649,6 @@ static int kvm_delete_memslot(struct kvm *kvm,
struct kvm_memory_slot *old, int as_id)
{
struct kvm_memory_slot new;
- int r;
if (!old->npages)
return -EINVAL;
@@ -1639,12 +1661,7 @@ static int kvm_delete_memslot(struct kvm *kvm,
*/
new.as_id = as_id;
- r = kvm_set_memslot(kvm, mem, old, &new, as_id, KVM_MR_DELETE);
- if (r)
- return r;
-
- kvm_free_memslot(kvm, old);
- return 0;
+ return kvm_set_memslot(kvm, mem, &new, as_id, KVM_MR_DELETE);
}
/*
@@ -1718,7 +1735,6 @@ int __kvm_set_memory_region(struct kvm *kvm,
if (!old.npages) {
change = KVM_MR_CREATE;
new.dirty_bitmap = NULL;
- memset(&new.arch, 0, sizeof(new.arch));
} else { /* Modify an existing slot. */
if ((new.userspace_addr != old.userspace_addr) ||
(new.npages != old.npages) ||
@@ -1732,9 +1748,8 @@ int __kvm_set_memory_region(struct kvm *kvm,
else /* Nothing to change. */
return 0;
- /* Copy dirty_bitmap and arch from the current memslot. */
+ /* Copy dirty_bitmap from the current memslot. */
new.dirty_bitmap = old.dirty_bitmap;
- memcpy(&new.arch, &old.arch, sizeof(new.arch));
}
if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE)) {
@@ -1760,7 +1775,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
bitmap_set(new.dirty_bitmap, 0, new.npages);
}
- r = kvm_set_memslot(kvm, mem, &old, &new, as_id, change);
+ r = kvm_set_memslot(kvm, mem, &new, as_id, change);
if (r)
goto out_bitmap;
--
2.33.1.1089.g2158813163f-goog
next prev parent reply other threads:[~2021-11-04 0:27 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-04 0:25 [PATCH v5.5 00/30] KVM: Scalable memslots implementation Sean Christopherson
2021-11-04 0:25 ` Sean Christopherson [this message]
2021-11-04 21:27 ` [PATCH v5.5 01/30] KVM: Ensure local memslot copies operate on up-to-date arch-specific data Ben Gardon
2021-11-04 22:41 ` Sean Christopherson
2021-11-09 0:37 ` Maciej S. Szmigiero
2021-11-09 1:17 ` Sean Christopherson
2021-11-04 0:25 ` [PATCH v5.5 02/30] KVM: Disallow user memslot with size that exceeds "unsigned long" Sean Christopherson
2021-11-09 0:38 ` Maciej S. Szmigiero
2021-11-04 0:25 ` [PATCH v5.5 03/30] KVM: Require total number of memslot pages to fit in an unsigned long Sean Christopherson
2021-11-09 0:38 ` Maciej S. Szmigiero
2021-11-04 0:25 ` [PATCH v5.5 04/30] KVM: Open code kvm_delete_memslot() into its only caller Sean Christopherson
2021-11-09 0:38 ` Maciej S. Szmigiero
2021-11-04 0:25 ` [PATCH v5.5 05/30] KVM: Resync only arch fields when slots_arch_lock gets reacquired Sean Christopherson
2021-11-09 0:38 ` Maciej S. Szmigiero
2021-11-04 0:25 ` [PATCH v5.5 06/30] KVM: Use "new" memslot's address space ID instead of dedicated param Sean Christopherson
2021-11-09 0:39 ` Maciej S. Szmigiero
2021-11-04 0:25 ` [PATCH v5.5 07/30] KVM: Let/force architectures to deal with arch specific memslot data Sean Christopherson
2021-11-09 0:39 ` Maciej S. Szmigiero
2021-11-09 1:13 ` Sean Christopherson
2021-11-04 0:25 ` [PATCH v5.5 08/30] KVM: arm64: Use "new" memslot instead of userspace memory region Sean Christopherson
2021-11-09 6:36 ` Reiji Watanabe
2021-11-04 0:25 ` [PATCH v5.5 09/30] KVM: MIPS: Drop pr_debug from memslot commit to avoid using "mem" Sean Christopherson
2021-11-04 0:25 ` [PATCH v5.5 10/30] KVM: PPC: Avoid referencing userspace memory region in memslot updates Sean Christopherson
2021-11-04 0:25 ` [PATCH v5.5 11/30] KVM: s390: Use "new" memslot instead of userspace memory region Sean Christopherson
2021-11-04 0:25 ` [PATCH v5.5 12/30] KVM: x86: " Sean Christopherson
2021-11-09 0:40 ` Maciej S. Szmigiero
2021-11-04 0:25 ` [PATCH v5.5 13/30] KVM: RISC-V: " Sean Christopherson
2021-11-04 0:25 ` [PATCH v5.5 14/30] KVM: Stop passing kvm_userspace_memory_region to arch memslot hooks Sean Christopherson
2021-11-09 0:40 ` Maciej S. Szmigiero
2021-11-04 0:25 ` [PATCH v5.5 15/30] KVM: Use prepare/commit hooks to handle generic memslot metadata updates Sean Christopherson
2021-11-09 0:40 ` Maciej S. Szmigiero
2021-11-04 0:25 ` [PATCH v5.5 16/30] KVM: x86: Don't assume old/new memslots are non-NULL at memslot commit Sean Christopherson
2021-11-09 0:40 ` Maciej S. Szmigiero
2021-11-04 0:25 ` [PATCH v5.5 17/30] KVM: s390: Skip gfn/size sanity checks on memslot DELETE or FLAGS_ONLY Sean Christopherson
2021-11-04 0:25 ` [PATCH v5.5 18/30] KVM: Don't make a full copy of the old memslot in __kvm_set_memory_region() Sean Christopherson
2021-11-09 0:41 ` Maciej S. Szmigiero
2021-11-04 0:25 ` [PATCH v5.5 19/30] KVM: x86: Don't call kvm_mmu_change_mmu_pages() if the count hasn't changed Sean Christopherson
2021-11-04 0:25 ` [PATCH v5.5 20/30] KVM: x86: Use nr_memslot_pages to avoid traversing the memslots array Sean Christopherson
2021-11-09 0:41 ` Maciej S. Szmigiero
2021-11-09 1:34 ` Sean Christopherson
2021-11-09 16:29 ` Maciej S. Szmigiero
2021-11-04 0:25 ` [PATCH v5.5 21/30] KVM: Integrate gfn_to_memslot_approx() into search_memslots() Sean Christopherson
2021-11-04 0:25 ` [PATCH v5.5 22/30] KVM: Move WARN on invalid memslot index to update_memslots() Sean Christopherson
2021-11-04 0:25 ` [PATCH v5.5 23/30] KVM: Resolve memslot ID via a hash table instead of via a static array Sean Christopherson
2021-11-11 23:51 ` Maciej S. Szmigiero
2021-11-12 1:03 ` Sean Christopherson
2021-11-04 0:25 ` [PATCH v5.5 24/30] KVM: Use interval tree to do fast hva lookup in memslots Sean Christopherson
2021-11-11 23:52 ` Maciej S. Szmigiero
2021-11-12 1:05 ` Sean Christopherson
2021-11-04 0:25 ` [PATCH v5.5 25/30] KVM: s390: Introduce kvm_s390_get_gfn_end() Sean Christopherson
2021-11-04 0:25 ` [PATCH v5.5 26/30] KVM: Keep memslots in tree-based structures instead of array-based ones Sean Christopherson
2021-11-11 23:52 ` Maciej S. Szmigiero
2021-11-12 0:51 ` Sean Christopherson
2021-11-13 15:22 ` Maciej S. Szmigiero
2021-11-04 0:25 ` [PATCH v5.5 27/30] KVM: Optimize gfn lookup in kvm_zap_gfn_range() Sean Christopherson
2021-11-04 0:25 ` [PATCH v5.5 28/30] KVM: Optimize overlapping memslots check Sean Christopherson
2021-11-04 0:25 ` [PATCH v5.5 29/30] KVM: Wait 'til the bitter end to initialize the "new" memslot Sean Christopherson
2021-11-11 23:52 ` Maciej S. Szmigiero
2021-11-04 0:25 ` [PATCH v5.5 30/30] KVM: Dynamically allocate "new" memslots from the get-go Sean Christopherson
2021-11-11 23:53 ` Maciej S. Szmigiero
2021-11-12 1:32 ` Sean Christopherson
2021-11-09 0:43 ` [PATCH v5.5 00/30] KVM: Scalable memslots implementation Maciej S. Szmigiero
2021-11-09 1:21 ` Sean Christopherson
2021-11-11 23:53 ` Maciej S. Szmigiero
2021-11-23 14:42 ` Maciej S. Szmigiero
2021-11-26 12:33 ` Paolo Bonzini
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